julianfoulger

Thursday I sailed through the Swiss emissions test. The results are better than before. All readings well within requirements but there is one reading that I find strange - that of HC (on previous tests around 20 ppm); I have over the last 6 months sorted out the stepper where I reduced from circa 50 steps down to 21 steps (MG Rover recommended).

The readings:

870 RPM, CO 0.00%, CO2 14.26%, HC -4 ppm
2,480 RPM, CO 0.00%, CO2 14.66%, HC -2 ppm

QU: How can on hydrocarbons the readings be minus parts per million? Max allowed under Swiss regs is +100 ppm.